1. What is the maximum value of the linear density in a crystalline solid (linear density defined as the fraction of the line length occupied by atoms, assumed as spheres and only counted it their center is on the line)?
2. What family of directions has the highest linear density in the FCC system?
3. What family of directions has the highest linear density in the BCC system?
4. What family of planes has the highest planar density in the FCC system?
5. What family of planes has the highest planar density in the BCC system?
6. What family of planes has the highest planar density in the HCP sytem?